One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,8)(5,6)(9,10)(11,15)(12,16)(13,14)(19,23)(21,24)(25,26,30,27)(28,33,36,31)(29,32,37,34)(35,39,40,38)(1,3)(2,4)(5,8)(6,7)(10,13)(15,16)(17,18,20,22)(19,21,23,24)(26,27)(29,37)(31,33)(35,40)(2,6)(4,7)(9,11,14,12)(10,15,13,16)(25,27,30,26)(28,33,36,31)(29,32,37,34)(35,38,40,39)(1,2)(3,4)(5,6)(7,8)(9,12,14,11)(10,15,13,16)(17,19)(18,21)(20,23)(22,24)(25,28,30,36)(26,31,27,33)(29,35,37,40)(32,38,34,39)(1,4)(2,3)(5,7)(6,8)(9,13,14,10)(11,15,12,16)(25,29)(26,32)(27,34)(28,35)(30,37)(31,38)(33,39)(36,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.